At present, liquid crystal display devices are widely used as display components in variety kinds of electronic products, and a backlight module is an important component in a liquid crystal display device.
In general, as shown in FIG. 1, a small and medium sized backlight module (different from the large sized ones) comprises a plastic frame 1, a reflective sheet 2, a light guide plate 3, an optical diaphragm 4, a light source flexible printed circuit 5 (LB FPC), an LED 6, a display screen 8 (cell) and a light-shielding tape 9. The light source flexible printed circuit 5 and the LED 6 are fixed to the light guide plate 3 and the plastic frame 1 by the light-shielding tape 9. With development of narrow frame display devices, a method that the plastic frame is replaced by an iron frame is proposed. Based on technical level at present, a thickness of the iron frame can reach as small as 0.1 mm, and therefore, a frame width of a display device can be greatly reduced compared with the case that when the plastic frame (with a thickness of 0.4 to 0.5 mm) is used. Besides, in order to further reduce the frame width, a method of removing frame sealant (light shielding sealant) is used. However, this design without plastic frame or light shielding sealant leads to the result that the optical diaphragm cannot be fixed.
In order to solve the above problem, it is necessary to provide a new backlight module.